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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 562 · 40 questions
TalentJR

How to do it in your head (Round, then work): Round each number: 2-digit numbers to the nearest ten, 3-digit numbers to the nearest hundred. Do the easy sum with the round numbers. Choose the option closest to your estimate.

NameDateTime takenScore ___ / 40
  1. 1.Best estimate of 31 × 43? (a) 12000 (b) 1200 (c) 120
  2. 2.Best estimate of 30 × 14? (a) 300 (b) 3000 (c) 30
  3. 3.Best estimate of 63 × 41? (a) 240 (b) 24000 (c) 2400
  4. 4.Best estimate of 51 × 28? (a) 15000 (b) 1500 (c) 150
  5. 5.Best estimate of 61 × 88? (a) 54000 (b) 5400 (c) 540
  6. 6.Best estimate of 83 × 12? (a) 80 (b) 800 (c) 8000
  7. 7.Best estimate of 121 + 387? (a) 700 (b) 300 (c) 500
  8. 8.Best estimate of 526 + 303? (a) 800 (b) 600 (c) 1000
  9. 9.Best estimate of 66 × 14? (a) 70 (b) 700 (c) 7000
  10. 10.Best estimate of 68 × 19? (a) 14000 (b) 1400 (c) 140
  11. 11.Best estimate of 74 × 84? (a) 560 (b) 56000 (c) 5600
  12. 12.Best estimate of 28 × 77? (a) 2400 (b) 240 (c) 24000
  13. 13.Best estimate of 84 × 40? (a) 3200 (b) 32000 (c) 320
  14. 14.Best estimate of 33 × 24? (a) 600 (b) 60 (c) 6000
  15. 15.Best estimate of 36 × 66? (a) 2800 (b) 280 (c) 28000
  16. 16.Best estimate of 149 + 752? (a) 900 (b) 1100 (c) 700
  17. 17.Best estimate of 81 × 34? (a) 2400 (b) 24000 (c) 240
  18. 18.Best estimate of 279 + 319? (a) 600 (b) 400 (c) 800
  19. 19.Best estimate of 874 + 660? (a) 1800 (b) 1400 (c) 1600
  20. 20.Best estimate of 611 + 139? (a) 900 (b) 700 (c) 500
  21. 21.Best estimate of 22 × 49? (a) 1000 (b) 10000 (c) 100
  22. 22.Best estimate of 97 × 30? (a) 300 (b) 30000 (c) 3000
  23. 23.Best estimate of 23 × 38? (a) 800 (b) 80 (c) 8000
  24. 24.Best estimate of 56 × 77? (a) 48000 (b) 480 (c) 4800
  25. 25.Best estimate of 856 + 687? (a) 1600 (b) 1400 (c) 1800
  26. 26.Best estimate of 93 × 66? (a) 6300 (b) 63000 (c) 630
  27. 27.Best estimate of 90 × 96? (a) 90000 (b) 9000 (c) 900
  28. 28.Best estimate of 613 + 672? (a) 1100 (b) 1300 (c) 1500
  29. 29.Best estimate of 59 × 98? (a) 600 (b) 6000 (c) 60000
  30. 30.Best estimate of 503 + 476? (a) 1200 (b) 1000 (c) 800
  31. 31.Best estimate of 424 + 157? (a) 600 (b) 400 (c) 800
  32. 32.Best estimate of 561 + 342? (a) 900 (b) 1100 (c) 700
  33. 33.Best estimate of 317 + 631? (a) 700 (b) 1100 (c) 900
  34. 34.Best estimate of 12 × 12? (a) 100 (b) 1000 (c) 10
  35. 35.Best estimate of 62 × 40? (a) 2400 (b) 24000 (c) 240
  36. 36.Best estimate of 528 + 264? (a) 600 (b) 1000 (c) 800
  37. 37.Best estimate of 715 + 487? (a) 1400 (b) 1000 (c) 1200
  38. 38.Best estimate of 13 × 51? (a) 500 (b) 5000 (c) 50
  39. 39.Best estimate of 295 + 527? (a) 800 (b) 600 (c) 1000
  40. 40.Best estimate of 758 + 241? (a) 1000 (b) 1200 (c) 800

Answer key

  1. 1200
  2. 300
  3. 2400
  4. 1500
  5. 5400
  6. 800
  7. 500
  8. 800
  9. 700
  10. 1400
  11. 5600
  12. 2400
  13. 3200
  14. 600
  15. 2800
  16. 900
  17. 2400
  18. 600
  19. 1600
  20. 700
  21. 1000
  22. 3000
  23. 800
  24. 4800
  25. 1600
  26. 6300
  27. 9000
  28. 1300
  29. 6000
  30. 1000
  31. 600
  32. 900
  33. 900
  34. 100
  35. 2400
  36. 800
  37. 1200
  38. 500
  39. 800
  40. 1000

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